Organic photovoltaic (OPV) device has become a worldwide research focus and is evaluated as one of the future key technologies for renewable energy. Over the last two decades, the solar conversion efficiency of these devices has enhanced significantly, in particular, through the development of solution-processed bulk heterojunction (BHJ) OPV cells. A lot of efforts have been devoted on the advancement of low-band gap donor materials. In contrast, there are far fewer high performance organic n-type acceptors materials reported for BHJ devices. Although many different types of donor polymers have been demonstrated with device efficiencies greater than 3%, these are limited to one or two acceptors based on the conventional C60 or C70 fullerene derivatives, such as PCBM, bis-PCBM, and ICBA.